If X + Y = 90^o, then express cos X in terms of simplest trigonometric ratio of Y.

Fill up the blanks :

(i) If sin 50^o=0.7660, then cos 40^o=……

(ii) If cos 44^o = 0.7193, then sin 46^o=…..

(iii) sin 50^o+cos 40^o = 2 sin (………)

(iv) Value of is ………

If A + B = 90^o, then express cos B in terms of simplest trigonometric ratio of A.

If A + B = 90^o, sin A = a, sin B = b, then prove that

(a) a² + b² = 1

(b)

Show that sin(50° + θ) – cos (40° – θ) = 0.